The date makes a lot of sense. Google uses its Nexus devices as a reference design and pushes out a new phone with every major Android update.
With Android Marshmallow on its final developer preview as of mid-August, the speculation seems to indicate that it'll be announced in a few short days. September 29 sounds about right.
Don't get your Google Wallet ready just yet. September is crowded (see: iPhone 6S). It probably won't be delivered until October, which is the same month the Nexus 6 2014 was unveiled. Rumors point to a pre-order date of October 13 in the US, while its worldwide availability is unclear.
Nexus 5 2015 price
The new Nexus 5 could once again give us a solid-performing phone at an affordable price, and that's a relief because last year's Nexus 6 bumped up the price considerably.
How much will the Nexus 5 2015 cost? While no one is certain, unconfirmed prices range between $300-400 (around £193-257 / AU$406-542), according to GizmoChina.
That's very comparable to the SIM-free Nexus 5 from two years ago, which retailed for $349 (£299, AU$399) without a contract. It's also a savings next to the Nexus 6, which cost $650 (£500, $870) at full retail when it came out almost a year ago.
Nexus 5 2015 design
Phone designs are trending in the direction of premium build materials, like the glass-and-metal Samsung Galaxy S6 and the leather-backed LG G4. That's not what we expect from Google's affordable handset, however.
Backing up this theory, we may have just gotten our first glimpse of the Nexus 5 2015, thanks to a leak out of Indonesia, and the photo jives with other rumors we've heard before. Previously, GizmoChina claimed that the new Nexus sports a matte plastic back cover. That's what we may be seeing in the blurry picture.
A clearer image claiming to show the back of the Nexus 5 2015 was posted by AndroidPit, and it looks very similar to the previous image we saw.
The image is a genuine photo, according to AndroidPit's anonymous source, and not a computer generated render. It shows a rear fingerprint sensor, raised camera lens and an LED flash. There's also further evidence in that photo that there will be a fingerprint sensor on the back. Android Pay, anyone?
That image was followed up by a shot showing the side of the phone, this time with an original Nexus 5 below it for comparison. They look very similar, but the new model is quite a bit slimmer and has differently positioned buttons.
Another image of the Nexus 5 (2015) was revealed by a case maker, this time giving us a good glance of what the front of the new device could look like.
It shows a front-facing selfie camera, front-facing speakers and two pretty thick bezels on the top and bottom of the screen, which means the new Nexus 5 (2015) probably isn't going to be the most compact or svelte of phones.
Other Nexus 5 2015 design rumors include front-facing speakers and an aluminium frame, though the side shot we've seen looks distinctly plastic.
Android Marshmallow is pushing USB Type C support for the first time, and the Nexus 5 could make a good example of its use. Why let the OnePlus 2 have all of the fun, being the only phone with this next-generation connector?
Renowned leaker account @OnLeaks also posted an image on Twitter that apparently shows the new Nexus 5 2015 in all its glory. The image ties in with other rumours we've heard about the Nexus 5 2015, and @OnLeak's reputation is pretty solid when it comes to revealing upcoming phones.
Display, specs, camera and battery life rumors
Nexus 5 2015 display
Expect an LG-made Nexus 5 to stick with a battery-friendly 1080p display instead of going the quad HD route that will likely be chosen for the new Nexus 6 2015.
That said, Nexus 5 rumors suggest that the screen technology will change from an IPS LCD to a P-OLED, and that it'll go from the 4.95-inch size we saw two years ago, to 5.2 inches.
Yes, it can still be called a Nexus 5, even with this minor adjustment. Phone manufacturers like round up or down when considering a device's name, so larger display isn't all too surprising.
Nexus 5 2015 specs
The new Nexus 5 may put "premium" in its internal specs instead of its body or display, and that seems to be what new benchmark leaks indicate.
It's pegged to have a Qualcomm processor, with rumors hinting at a Snapdragon 808 hexa-core processor, like the LG G4 (that makes sense) – or, if we're lucky, a Snapdragon 820.
The Snapdragon 820 chip may be saved for the Nexus 6 2015, but a new Nexus 5-linked benchmark test would have you think – and hope – otherwise.
The best phones in the latter half of 2015 are boosting their performance with 4GB RAM, and that's what has been tipped for the Nexus 5 2015. That's double the memory two years ago.
Nexus 5 2015 camera
If there's one thing Google needs to get right with its next Nexus, it's making a phone with a great camera. Nexus fans have consistently complained about mediocre photos.
There's a little more confidence behind the Nexus 5 camera knowing that LG may be in charge of the device again. The firm really stepped up its sensor and post-processing game with the LG G4.
Rumors point to a 13MP snapper on back, with a wide f/1.8 aperture lens, LG's advanced laser autofocus, optical image stabilisation and a dual-LED flash.
Save for the 16MP sensor and the dual-LED flash, these camera specs matches the LG G4. Next to the Samsung Galaxy S6 and the newer Galaxy Note 5, it's the best smartphone camera out there.
Nexus 5 2015 battery life
The Nexus 5 2013 battery life was the phone's second biggest problem, and LG may address that by upping the capacity from 2,300mAh to 2,700mAh or even 3,180mAh.
This giant leap would actually best the LG G4 battery, that's an even 3,000mAh, despite the company's 5.5-inch flagship having more room.
Now, if LG could do a better job of reducing its handset battery drain, that would be perfect. The G4 had issues with background tasks eating away at otherwise solid battery capacity.
The Android Marshmallow release date looks ready for September 29, and that almost certainly means that the LG-made Nexus 5 2015 launch will be then too. We'll keep updating this page with all of the rumors until Google makes the big announcement.